Shuffle and deal out 21 cards.
Pick a Card: Have someone choose and remember a card, then return it to the deck.

Shuffle the 21 cards again.
Deal into 3 piles and ask which pile has their card.

Pick up the piles, placing their pile in the middle.
Repeat step 2 two more times.

Deal the cards into 3 piles and count. The 11th card is theirs!